Add support for Go1.16 embed.FS

This just adds a new struct with embed.FS and slightly changes
findMigrations() to also have a root from where to start searching.

Author: cryptix

migrate.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"os"
 	"path"
+	"path/filepath"
 	"regexp"
 	"sort"
 	"strconv"
@@ -229,7 +230,7 @@ type HttpFileSystemMigrationSource struct {
 var _ MigrationSource = (*HttpFileSystemMigrationSource)(nil)
 
 func (f HttpFileSystemMigrationSource) FindMigrations() ([]*Migration, error) {
-	return findMigrations(f.FileSystem)
+	return findMigrations(f.FileSystem, "/")
 }
 
 // A set of migrations loaded from a directory.
@@ -241,13 +242,13 @@ var _ MigrationSource = (*FileMigrationSource)(nil)
 
 func (f FileMigrationSource) FindMigrations() ([]*Migration, error) {
 	filesystem := http.Dir(f.Dir)
-	return findMigrations(filesystem)
+	return findMigrations(filesystem, "/")
 }
 
-func findMigrations(dir http.FileSystem) ([]*Migration, error) {
+func findMigrations(dir http.FileSystem, root string) ([]*Migration, error) {
 	migrations := make([]*Migration, 0)
 
-	file, err := dir.Open("/")
+	file, err := dir.Open(root)
 	if err != nil {
 		return nil, err
 	}
@@ -259,7 +260,7 @@ func findMigrations(dir http.FileSystem) ([]*Migration, error) {
 
 	for _, info := range files {
 		if strings.HasSuffix(info.Name(), ".sql") {
-			migration, err := migrationFromFile(dir, info)
+			migration, err := migrationFromFile(dir, root, info)
 			if err != nil {
 				return nil, err
 			}
@@ -274,8 +275,8 @@ func findMigrations(dir http.FileSystem) ([]*Migration, error) {
 	return migrations, nil
 }
 
-func migrationFromFile(dir http.FileSystem, info os.FileInfo) (*Migration, error) {
-	path := fmt.Sprintf("/%s", strings.TrimPrefix(info.Name(), "/"))
+func migrationFromFile(dir http.FileSystem, root string, info os.FileInfo) (*Migration, error) {
+	path := filepath.Join(root, info.Name())
 	file, err := dir.Open(path)
 	if err != nil {
 		return nil, fmt.Errorf("Error while opening %s: %s", info.Name(), err)

migrate_go116.go

@@ -0,0 +1,22 @@
+// +build go1.16
+
+package migrate
+
+import (
+	"embed"
+	"net/http"
+)
+
+// A set of migrations loaded from an go1.16 embed.FS
+
+type EmbedFileSystemMigrationSource struct {
+	FileSystem embed.FS
+
+	Root string
+}
+
+var _ MigrationSource = (*EmbedFileSystemMigrationSource)(nil)
+
+func (f EmbedFileSystemMigrationSource) FindMigrations() ([]*Migration, error) {
+	return findMigrations(http.FS(f.FileSystem), f.Root)
+}

migrate_go116_test.go

@@ -0,0 +1,29 @@
+// +build go1.16
+
+package migrate
+
+import (
+	"embed"
+
+	. "gopkg.in/check.v1"
+)
+
+//go:embed test-migrations/*
+var testEmbedFS embed.FS
+
+func (s *SqliteMigrateSuite) TestEmbedSource(c *C) {
+	migrations := EmbedFileSystemMigrationSource{
+		FileSystem: testEmbedFS,
+		Root:       "test-migrations",
+	}
+
+	// Executes two migrations
+	n, err := Exec(s.Db, "sqlite3", migrations, Up)
+	c.Assert(err, IsNil)
+	c.Assert(n, Equals, 2)
+
+	// Has data
+	id, err := s.DbMap.SelectInt("SELECT id FROM people")
+	c.Assert(err, IsNil)
+	c.Assert(id, Equals, int64(1))
+}